Step for spiral stairways.



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PIERRE DUV INAGE, F IBROQKLYN, YORK.

STEP FOR SPIRAL STAIRWAYS.

a stairway lwhich will occupy'com'paratively little space; and the object ofmy invention is to provide a step made of cast material so` constructed that each step will have the necessary sustaming strength when supported V at the inner end only and at the same time a stairway will be provided all parts of whichVV will be available for ascent or descent; a further object of my' invention being to provide a step so constructed that but a single pattern will be needed in building either a right or left stairway.

The invention is illustrated in the accompanying drawing, in which- Figure 1, is a longitudinal vertical section of a step constructed in accordance with my invention, the supporting riser being shown in full lines;

Fig. 2, is a transverse section of the step, on the lines 2-2, of Figs. l, and 3;

Fig. 3, is a plan view of the step, with a portion of another step superimposed thereon, illustrating how the steps are arranged in a stairway winding to the right in ascent; and l Fig. 4, is a view similar to Fig. 3, showing how the steps are arranged winding to the left in ascent.

In the drawing, like numerals of reference refer to the same parts -in each of the views.

In practice I provide a step consisting of a tread 5, comprising a divergent part 6, and a .part 7, with substantially parallel sides ending in a hub 8, with a cylindrical passageway 9, therethrough whereby means are provided for mounting the step on a vertical shaft, as will be understood; and each step may have a boss 1 0, arranged in any desired position, each having a passageway 11, through which a set screw may pass to engage the shaft, or column on which the step is mounted, whereby the step will be held in xed position, as will be understood.

The step is provided with a central'rib, or riser' 12, which extends from the hub' 8,

Spcification of Letters Patent. 1

Patented Feb. 13, 1917.-

Appiieation mea December '2, l1915. 4 serial No. 64,728.

to the outer .endv of they step, asl'v'clear'ly vshownin Fig. 1. As the hub' 8,' has considerablelength, the riser '12, extends downward a considerable distance on the same without interfering with the step below, and can rise from this pointto the outer end of the Step in a manner toform a firm brace, or support for the tread thereby making it unnecessary to support the step at'the outer end, as will b efclear. n v v k.The step is also provided with ribs 13,'and 14, which extend respectively on the opposite sides of the' Vfia-ring. part 6, in a substantially radial manner from the center of the hub 8or axis thereof, as the inner edge of eachrib is on a radial line from the axisof the hub; and the outerendsfof the ribs 13, and 14, are connected by a rib 15, whereby the entire. step is strengthened, as will be understood.

The edges 16, and 17, of the step convergev .low the rib 14, of the next step,`according as the steps windto the right or left, which can be readily done since the ribs are substantially radially disposed on the steps. This provides for the necessary lapping of the edges of the successive stepsthe proper stiffening of the step where the greatest strain occurs, and they most effective exposure of each step for the foot.

As each step comprises the flaring part 6, and part 7, .with parallel sides, when the steps are superimposed, as in a stairway,

with the successive ribs 13, .and 14, vertically disposed, as clearly shown in Figs. 3, and 4, one of the parallel edges 18, or 19, of the parallel part will transversely extend across the face of the step below substantially parallel with a tangent of the stairway, as clearly shown in Figs. 3 and 4, By this construction, a person walking down the stairway adjacent to the inner post, will have `his steps directed toward the periphery of the stairway, as the edge of the step adjacent the central post is parallel with a tangent of the stairway, and lit is natural to step from a step facing the edge. Following this tendency would carry the person outward toward the periphery of thestairway, as will be understood, where the tread surface of the step is broader. Thus, by making the inner portion of the step with edges tangential to the hub, and parallel with each other, and, consequently, parallel with a tangent of the stairway, I provide a stairway that is easier to ascend, or descend close to the central post thereby greatly increasing the capacity of the stairway, and reducing the necessity of lengthening the steps for the sake of capacity. This also reduces the liability of any object sliding down the stairway for the reason that when the object leaves oneV step, as here constructed, it will be directed toward the periphery of the stairway more than would be the case if the edges of each step extended radially from the hub, or even in a straight line tangentially from the hub to the outer end.

By making the steps in the way de-l the steps whether the steps wind to the right, or left in ascending, as willbe clear.

o The step is simple in construction, easy to manufacture, and efficient in use.

I claim:

1. A step for a spiral stairway, said step having a hub, and having edges adjacent to said hub parallel to each other and extending a suicient distance from the hub that a perpendicular erected thereto will traverse the periphery of the second lower step in a stairway, said step having edges diverging from said parallel sides. K

2. A step for a spiral stairway, said step having a hub, and having parallel edges adff jacent to the hub and tangential thereto, said edges extending a suiiicient distance from the hub that a perpendicular erected thereto will-traverse the periphery of the second lower step in a stairway, said step having edges diverging from said parallel sides. v

Dated this 30th day of September, 1915.

PIERRE DUVINAGE.

Copies of this patent may be obtained for ve cents each, by addressing'the Commissioner of Patents,

Washington,v ID. G. 

